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450
Democritus
450 B.C.
Democritus creates the first atomic theroy that all matter is made up of particles called atoms -
Period: 450 to
History Of the Atom
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John Dalton, Atomic theroy
John Dalton comes up with an updated atomic theroy in which there are spherical solid atoms based upon measurable properties of mass -
Law of Definite Proportions
Joseph Proust states that a chemical compound always contains the exact same proportion of elements by mass -
Plum Pudding Model
J.J. Thomson proposed a model in which a disperesed positive charge in the atom balances out the electrons that dot the atom making it look akin to plum pudding -
R. A. Milika, Oil Drop experiment
R. A. Milika preforms the Oil Drop Experiment, the experiment proves the mass and charge of an electron -
Gold Foil Experiment
Ernest Rutheford prefroms the Gold foil experiment, using alpha particles and shooting them at a piece of gold foil he finds that some reflect back he discovers the nucleus and disproves the plum pudding model -
Nuclear model
Rutherford with his results of the Gold Foil experiment creates a new model in which the atom has a relativly high central charge concentrated into a very small volume in comparison to the rest of the atom, The central part contains most of the atomic mass -
The Bohr Model
Niels Bohr creates a model in which the electrons orbit the nucleus simular to the solar system and stay in thier "orbits" due to atraction by electrostatic forces -
Spherical Model
M. Kac proposes the Spherical Model, the Spherical Model is a model of ferromagnetism that when applied to systems of dimension greater than four the critical exponents that govern the behavior of the system near the critical point can be solved -
Quantum Mechanical Model
Erwin Shcrodinger creates a model that uses mathmatics to describe the likelihood of finding an electron in a certain position -
Uncertainty Principle
Heisnburg explains that the uncertainty principle is a variety of mathmatical ineualities asserting a fundemental limit to the precision with which certain pairs of physical porportions of complementry varibles can be know i.e postion and momentum of electrons -
Paul Dirac
Paul Dirac formulated the Dirac equation, which describes the behaviour of fermions and predicted the existence of antimatter. -
Discovery of the nuetron
James Chadwick uses alpha particles to find a nuetral atomic particle with mass close to that of a proton that resides in the nucleus, he names it the nuetron